Designation E1603/E1603M − 11 (Reapproved 2017) Standard Practice for Leakage Measurement Using the Mass Spectrometer Leak Detector or Residual Gas Analyzer in the Hood Mode1 This standard is issued u[.]
Trang 1Detector or Residual Gas Analyzer in the Hood Mode
This standard is issued under the fixed designation E1603/E1603M; the number immediately following the designation indicates the year
of original adoption or, in the case of revision, the year of last revision A number in parentheses indicates the year of last reapproval.
A superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1 Scope
1.1 This practice covers procedures for testing the sources
of gas leaking at the rate of 1 × 10−8 Pa m3/s (1 × 10−9
standard-cm3/s at 0°C) or greater These test methods may be
conducted on any object that can be evacuated and to the other
side of which helium or other tracer gas may be applied The
object must be structurally capable of being evacuated to
pressures of 0.1 Pa (approximately 10−3torr)
1.2 Three test methods are described;
1.2.1 Test Method A—For the object under test capable of
being evacuated, but having no inherent pumping capability
1.2.2 Test Method B—For the object under test with integral
pumping capability
1.2.3 Test Method C—For the object under test as in Test
Method B, in which the vacuum pumps of the object under test
replace those normally used in the leak detector (LD)
1.3 Units—The values stated in either SI or std-cc/sec units
are to be regarded separately as standard The values stated in
each system may not be exact equivalents: therefore, each
system shall be used independently of the other Combining
values from the two systems may result in non-conformance
with the standard
1.4 This standard does not purport to address all of the
safety concerns, if any, associated with its use It is the
responsibility of the user of this standard to establish
appro-priate safety and health practices and determine the
applica-bility of regulatory limitations prior to use.
1.5 This international standard was developed in
accor-dance with internationally recognized principles on
standard-ization established in the Decision on Principles for the
Development of International Standards, Guides and
Recom-mendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee.
2 Referenced Documents
2.1 ASTM Standards:2
E1316Terminology for Nondestructive Examinations
2.2 ASNT Standards:3
SNT-TC-1ARecommended Practice for Personnel Qualifi-cation and CertifiQualifi-cation in Nondestructive Testing
ANSI/ASNT-CP-189Standard for Qualification and Certifi-cation of Nondestructive Testing Personnel
2.3 Military Standard:
MIL-STD-410 Nondestructive Testing Personnel Qualifica-tion and CertificaQualifica-tion4
2.4 AIA Standard:
NAS-410Certification and Qualification of Nondestructive Test Personnel5
3 Terminology
3.1 Definitions—For definitions of terms used in this
practice, see TerminologyE1316
4 Summary of Practice
4.1 These test methods covered in this practice require a helium LD that can provide a system sensitivity of 10 % or less
of the intended leakage rate to be measured
4.2 Test Method A—This test method is used to helium leak
test objects that are capable of being evacuated to a reasonable test pressure by the LD pumps during an acceptable length of time (seeFig 1) This requires that the object be clean and dry Auxiliary vacuum pumps having greater capacity than those in the LD may be used in conjunction with them The leak test sensitivity will be reduced under these conditions
1 This practice is under the jurisdiction of ASTM Committee E07 on
Nonde-structive Testing and is the direct responsibility of Subcommittee E07.08 on Leak
Testing Method.
Current edition approved June 1, 2017 Published July 2017 Originally approved
in 1994 Last previous edition approved in 2011 as E1603 - 11 DOI: 10.1520/E1603
_E1603M-11R17.
2 For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website.
3 Available from American Society for Nondestructive Testing (ASNT), P.O Box
28518, 1711 Arlingate Ln., Columbus, OH 43228-0518, http://www.asnt.org.
4 Available from Standardization Documents Order Desk, DODSSP, Bldg 4, Section D, 700 Robbins Ave., Philadelphia, PA 19111-5098, http:// dodssp.daps.dla.mil.
5 Available from Aerospace Industries Association of America, Inc (AIA), 1000 Wilson Blvd., Suite 1700, Arlington, VA 22209-3928, http://www.aia-aerospace.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959 United States
Trang 24.3 Test Method B—This test method is used to leak test
equipment that can provide its own vacuum (that is, equipment
that has a built-in pumping system) at least to a level of a few
hundred pascals (a few torr) or lower Refer toFig 2
4.4 Test Method C—When a vacuum system is capable of
producing internal pressures of less than 2 × 10−2Pa (2 × 10−4
torr) in the presence of leaks, these leaks may be located and
evaluated by the use of either a residual gas analyzer (RGA) or
by using the spectrometer tube and controls from a
conven-tional MSLD, provided that the leakage is within the sensitivity
range of the RGA or MSLD under the conditions existing in the
vacuum system Refer toFig 3
5 Significance and Use
5.1 Test Method A—This test method is the most frequently
used in leak testing components Testing of components is
correlated to a standard leak, and the actual leak rate is
measured Acceptance is based on the maximum system
allowable leakage For most production needs, acceptance is
based on acceptance of parts leaking less than an established
leakage rate, which will ensure safe performance over the
projected life of the component Care must be exercised to
ensure that large systems are calibrated with the standard leak
located at a representative place on the test volume As the
volume tends to be large (>1 m3) and there are often low
conductance paths involved, a check of the response time as
well as system sensitivity should be made
5.2 Test Method B—This test method is used for testing
vacuum systems either as a step in the final test of a new
system or as a maintenance practice on equipment used for
manufacturing, environmental test, or conditioning parts As
with Test Method A, the response time and a system sensitivity check may be required for large volumes
5.3 Test Method C—This test method is to be used only
when there is no convenient method of connecting the LD to the outlet of the high-vacuum pump If a helium LD is used and the high-vacuum pump is an ion pump or cryopump, leak testing is best accomplished during the roughing cycle, as these pumps leave a relatively high percentage of helium in the high-vacuum chamber This will limit the maximum sensitivity that can be obtained
6 Basis of Application
6.1 Personnel Qualification—If specified in the contractual
agreement, personnel performing examinations to these test methods shall be qualified in accordance with a nationally recognized NDT personnel qualification practice or standard, such as ANSI/ASNT-CP-189, SNT-TC-1A, MIL-STD-410, NAS-410, or a similar document and certified by the employer
or certifying agency, as applicable The practice or standard used and its applicable revision shall be identified in the contractual agreement between the using parties
7 Interferences
7.1 Series leaks with an unpumped volume between them present a difficult if not impossible problem in helium leak testing Although the trace gas enters the first leak readily enough since the pressure difference of helium across the first leak is approximately one atmosphere, it may take many hours
to build up the partial pressure of helium in the volume between the two leaks so that enough helium enters the vacuum system to be detected by the LD This type of leak occurs frequently under the following conditions:
7.1.1 Double-welded joints and lap welds, 7.1.2 Double O-rings,
7.1.3 Threaded joints, 7.1.4 Ferrule and flange-type tubing fittings, 7.1.5 Casting with internal voids,
7.1.6 Flat polymer gaskets, and 7.1.7 Unvented O-ring grooves
FIG 1 Test Method A
FIG 2 Test Method B
FIG 3 Test Method C
Trang 3flux, grease, paint, etc are common problems These problems
can be eliminated to a large extent by proper preparation of the
parts before leak testing Proper degreasing, vacuum baking,
and testing before plating or painting are desirable
7.4 The time constant for evacuation and for the rise of the
helium signal is inversely proportional to the pumping speed
and directly proportional to the volume being evacuated
Low-conductance tubing, or any other flow impedance, can
reduce the pumping speed of the system very significantly, thus
extending the system response time constant If such an
impedance connects two volumes under test, a LD connection
to each volume should be provided
7.5 When unusually long pumping times are necessary, all
of the connections not being tested should be protected from
continuous exposure to the helium This will reduce undesired
high-helium background levels due to permeation of helium
through the O-rings This can be effected by double-seals (with
evacuation of the space between), or sometimes by more
informal shielding approaches
TEST METHOD A—HELIUM LEAK TESTING OF
COMPONENTS/SYSTEMS USING THE LD
8 Apparatus
8.1 Leak Detector, having a minimum detectable leak rate as
required by the test sensitivity
8.2 Auxiliary Pumps, capable of evacuating the object to be
tested to a low enough pressure that the LD may be connected
8.3 Suitable Connector and Valves, to connect to the LD test
port Compression fitting and metal tubing should be used in
preference to a vacuum hose
8.4 Standard Leaks of Both Capsule Type (Containing Its
Own Helium Supply) and Capillary Type, an actual leak that is
used to simulate the reaction of the test system to a helium
leak The leak rate of the standard leak used for the system
calibration shall be equal to or less than the acceptance level
(maximum permissible leakage rate) Temperature correction
of the permeation capsule-type standard leaks should be
performed when the ambient temperature has a difference of
3°C [5°F] from the calibration temperature of the standard
leak The leakage rate error may become significant (>12 %)
without temperature correction
8.5 Vacuum Gauge, to read the pressure before the LD is
connected when using an auxiliary roughing pump
8.6 Helium Tank and Regulator, with attached helium probe
hose and jet for locating leaks
rate from the capsule leak to equilibrate The permeation-type capsule leak should be stored with the shutoff valve (if present) open, and the leak should be allowed to equilibrate to ambient temperature for several hours
9.2 Adjust the LD readout to correspond to the temperature-corrected standard leak value in accordance with the manufac-turers’ instructions
N OTE 1—Valve closures may be accomplished automatically on some LDs, and some counterflow-type MSLDs require continued use of the roughing pump during testing Refer to the manufacturer’s operating manual.
9.3 Disconnect the capsule standard leak from the LD and connect the test system to the LD
9.4 Instrument calibration shall be performed prior to and upon completion of each test Any change in sensitivity shall
be evaluated to determine if the test results are valid
10 System Calibration and Test Procedure
10.1 For small-volume tests (a few litres and less) or when the standard leak cannot be attached directly to the test component, the instrument calibration shall be used for the system calibration The correction factor (CF) used to multiply the instrument calibration value for the system leak rate is one 10.2 For large-volume systems, attach one of the standard leaks to the test system at a location that provides the lowest conductance path to the LD
N OTE 2—If using a capsule leak, open the calibrated leak (CL) and pump isolation valves, and close the calibration valve Turn on the CL vacuum pump Refer to Fig 4
10.3 Evacuate the device to be tested until near equilibrium pressure is reached on the rough vacuum gauge Open the valve to the LD and check the background helium concentra-tion When the helium background is equal to or less than one half the acceptance level (maximum permissible leakage rate) and stable, close the valve(s) to the roughing pumps
10.4 System Calibration or Procedure Qualification:
10.4.1 Record the helium background level
10.4.2 Open the valve of the system standard leak (calibra-tion valve) attached to the test component/system (Fig 4)
N OTE 3—If using a capillary leak, apply helium of one atmosphere to the standard leak For the capsule standard leaks, close the pump isolation valve immediately prior to opening the calibration valve.
10.4.3 Graph the LD response as a function of time until a steady-state condition is reached Refer to Fig 5
10.4.4 Close the standard leak valve, and reduce the helium background of the test component/system to the same level as that obtained before system calibration It may be necessary to
Trang 4open roughing pump valves and use the roughing pumps to
expedite the reduction of the helium background
10.4.5 Calculate the LD CF for adjusting the instrument
calibration reading to a system calibration reading For tests on
large-volume systems, the amplitude response of a leak in the
system is less than the amplitude response from the instrument
calibration standard leak
10.4.5.1 This CF should be calculated at either the time at
which a steady-state response (SS) is reached or at the time at
which the LD response is 63 % of the change This shall be the
minimum test period The formula for the CF at this test time
is as follows:
where:
CL c = temperature-corrected standard leak rate,
LR = indicated LD reading (0.63 SS or SS) at the end of the
test period (τ or 5τ respectively), and
BR = background reading (initial reading)
10.5 Set the LD on the appropriate range
10.6 Close the valves to the roughing pump(s) if they were opened to expedite the reduction of the helium background 10.7 Fill the test component/system enclosure with helium
or place the test part in the enclosure Large enclosures should
be purged sufficiently to remove the trapped air For any concentration other than 100 % helium atmosphere, the system acceptance level shall be adjusted for the reduced sensitivity by the following formula:
where:
LR ACC = system acceptance leakage rate
LR s = test specification leakage rate
%C = helium concentration
N OTE 4—Stratification of the tracer gas should be taken into consider-ation and helium concentrconsider-ation must be measured at the lowest locconsider-ation in the hood.
10.8 Keep the test component/system in the test enclosure for the test period established in accordance with 10.4.5 and record the LD reading at the end of the period
N OTE 5—The system time response may be longer than the instrument response time.
10.9 Calculate the system leakage by multiplying the LD reading by the CF to obtain the corrected system leakage For tests in which a system calibration was not performed (that is, test volumes less than a few litres), use a CF of one
10.10 Write a test report, or otherwise indicate the test results as required
TEXT METHOD B—HELIUM LEAK TESTING OF VACUUM EQUIPMENT AND SYSTEMS THAT HAVE INTEGRAL PUMPING SYSTEMS OF THEIR OWN
11 Apparatus
11.1 Helium LD—Same apparatus as Section8
12 Preparation of Apparatus
12.1 Connect the inlet valve of the LD of the foreline of the object to be tested If possible, insert a valve in the foreline between the mechanical pump and the LD connection All connections should have as high a conductance as is practical 12.2 Attach the standard leak to the object to be tested and
as far as practical from the inlet to the pumping system Refer
toFig 4 12.3 Operate the equipment until equilibrium vacuum is reached in the vacuum chamber
12.4 Slowly open the inlet valve to the LD Do not allow the
LD pressure to exceed the manufacturer’s recommendations 12.5 If the inlet valve can be opened fully without exceed-ing the safe LD operatexceed-ing pressure, close the equipment roughing pump valve slowly If this valve can be closed completely, the maximum sensitivity of the test will be achieved
13 Instrument Calibration
13.1 See Section9
FIG 4 Calibration Setups
Trang 514 System Calibration and Test Procedure
14.1 See Section10
TEST METHOD C—USE OF RGA OR OF HELIUM
MSLD SPECTROMETER TUBE AND CONTROL IN
LEAK TESTING (NO VACUUM SYSTEM IN THE LD)
15 Apparatus
15.1 RGA or MSLD and Controls, tuneable to the trace gas.
15.2 Standard Leak, of approximately the size of the
mini-mum leak to be located
15.3 Suitable Fitting and Isolating Valves, for attachment to
the high-vacuum chamber
15.4 Liquid Nitrogen Cold Traps, to be used if the system
contains condensable vapors harmful to the RGA or the
MSLD
16 Preparation of Apparatus
16.1 Attach the RGA or the MSLD tube to the high-vacuum
section of the test object to be tested The connection should be
located near the pumped end of the system and attached with
as short and as large a diameter tube as practical Maximum
test sensitivity is obtained when the high-vacuum pumps are
throttled, by means of the high-vacuum valve, so as to maintain
as high a pressure in the volume under test as is safe for the
LD An isolation valve may be used between the detector and the system to allow servicing the detector without loss of vacuum in the system and to protect the detector from contamination when not in use When a liquid nitrogen trap and isolating valve are both being used, the cold trap should be located between the test object and the isolating valve 16.2 Attach a standard capillary or permeation leak to the system as far away from the pumps as possible, using the lowest conductance path A small high-vacuum valve should be used between the standard leak and the system, and a dust cap should be provided for the capillary standard leak if it is to be left in place Refer toFig 4for the calibration setup
17 Instrument Calibration
17.1 See Section9
18 System Calibration and Test Procedure
18.1 See Section10
19 Keywords
19.1 helium leak test; helium mass spectrometer leak test; hood leak test; leak testing; mass spectrometer leak test
FIG 5 System Time Constant
Trang 6ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentioned
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